Well, Nintendo had not worked with them in 6 years.

iRacing is subscription based online racing. It's very much sim oriented.
It's where GT Sport players go after they had enough of the punters and rammers...

iRacing has actual stewards to review incidents and you can get suspended and/or demoted if you can't behave yourself on the track. It's very strict, shared fault with damage. Unfortunately all that keeps the population low, not the game you jump into for a quick round.

A friend of mine plays it

Multi screen support, and a good wheel and pedals is pretty much required.

So kinda baffling what they want with Monster games, seems to be the polar opposite. Maybe to make a more accessible racing game?

ExciteBots was one of the best experiences I had on a video game, period. So good I recently found out that the old community went back to it through emulation and/or reenabling software for the Wii Online features. These Monster Games guys are way too talented (or were, back in the day; I cannot know). I can't believe Nintendo never made a move to acquire them.